1. Field of the Invention
The present invention relates to a webbing locking device for locking an intermediate portion of an occupant restraining webbing, adapted for use in a seatbelt system for restraining an occupant of a vehicle, particularly, suitable to assemble the same into a webbing retractor disposed on a ceiling of the vehicle.
2. Description of the Prior Art
A webbing retractor is constructed such that a a webbing takeup shaft is secured with one end portion of an occupant restraining webbing and it is rotated in a direction of a webbing winding by a biasing force of a spiral spring so that the webbing can be wound in layers on the takeup shaft. Also, the webbing retractor is generally fixed to a side wall of the vehicle and the webbing which has been unwound from the takeup shaft is turned back at a slip joint mounted on an upper portion of the vehicle and, thereafter, it is applied to the occupant as a shoulder webbing.
In such a seatbelt system, since the webbing is turned back sharp at the slip joint, there is such a problem that a frictional resistance between the webbing and the slip joint is increased when the webbing is moved.
In order to overcome the above problem such a system has been proposed that the webbing retractor is mounted on a side of the ceiling or an upper side of a center pillar of the vehicle and the webbing is drawn out through an opening of a panel of the ceiling or the center pillar. In this case the webbing is slightly turned at the opening, an angle of which is small, so that a frictional resistance between the webbing and the opening becomes small when the webbing is moved.
On the other hand, the webbing retractor is generally provided therein with a webbing locking device for preventing the webbing from unwinding in an emergency situation of the vehicle. The webbing locking device can roughly be classified in two type, one type being directed to a locking mechanism comprising a combination of a ratchet wheel fixed to the takeup shaft and a pawl engaged with the ratchet wheel and the other type being directed to a locking mechanism disposed adjacent to the webbing retractor, in which a pair of lock members clip, or lock, the webbing in the emergency situation of the vehicle.
In the former type mechanism, however, there is such a problem that a winding diameter of the webbing retactor must be made large. In the latter type, also, there is such a fear that when a large drawing-out force acts upon the webbing the webbing is slipped out and there is such a problem that such acceleration sensing means as an inertia weight can not be applied directly to the same since a large force is required in order to operate the pair of lock members.